Ablation of myocardial tissue is well known as a treatment for cardiac arrhythmias. In radio-frequency (RF) ablation, for example, a catheter is inserted into the heart and brought into contact with tissue at a target location. RF energy is then applied through an electrode on the catheter in order to create a lesion for the purpose of breaking arrhythmogenic current paths in the tissue. Recently, circumferential ablation of the ostia of the pulmonary veins has gained acceptance as a treatment for atrial arrhythmias, and particularly for atrial fibrillation.
As another example, a renal ablation procedure may involve the insertion of a catheter having multiple RF electrodes at its distal end into a renal artery in order to complete a circumferential or helical lesion in the artery in order to denervate the artery for the treatment of hypertension.
Contact with the tissue to be treated is critical to the success of the ablation procedure. Often, the practitioner is not certain that each of the electrodes is in contact with the tissue thereby causing delays in the procedure as well an ineffective result. In all of these procedures, whether using an ablation catheter or balloon, it is difficult to determine if each of the ablation electrodes has made contact with the tissue to be treated, especially in a multi-electrode device. Many times, the procedure may have to be repeated to make sure the ablation is complete. Repeated procedures increase the discomfort of the patient as well as an increase in the cost.
Some prior art devices may include a sensor for at or near a tip electrode to indicate contact with the treatment site. However, in a multi-electrode catheter or multi-electrode balloon catheter, contact sensors that readily indicate that contact has been made for each electrode are not available.
Accordingly, it would be desirable to provide an ablation catheter that has at least one sensor to easily detect if the electrode is in contact with the tissue. Likewise, it would be desirable to provide the practitioner with an easily readable indication of contact. As will be described in the following materials, this disclosure satisfies these and other needs.